The conventional telephony network allows users to communicate with each other through a central system of switches, which can be referred to as a telephone exchange. The telephone exchanges provide electrical or optical switches to connect users and allow communication. The conventional telephony network is often referred to as a public switched telephone network (PSTN). The switches and other equipment necessary to make a connection can be located, for example, in central offices (COs) and in customer premises. The PSTN can have local exchanges that allow a user to call another user of the PSTN through COs of the local exchange. The PSTN can also have long lines that allow long distance call transmission, such that a user can call another user on the PSTN that is not part of the local exchange. In this case, the call may be routed through multiple COs until the call reaches the called party's local exchange.
Telephone service providers generally provide subscribing users of the PSTN with additional services. A service is an extension of basic call handling that provides for special treatment of the call at the originating end, the terminating end or both. Some examples of services are call forwarding, call transfer, three-way calling and caller ID. Many different types of services are created to provide ways for users to specially treat a call based on user preference. For example, users can choose to have their calls forwarded if they are away from their phone. A user may put a call on hold and transfer the call to another user.
An extension of the PSTN is a private branch exchange (PBX). A PBX is a circuit-switched, intra-enterprise switching system. Unlike the PSTN, the PBX provides a user of the PBX with the ability to call another user of the PBX without having to go through a CO. In this manner, a PBX provides a group of users of the PBX with their own exchange. For example, a corporation may have a PBX that allows the employees to call each other through the PBX. A PBX may also provide for the interaction of users of the PBX and external users. For example, a PBX may have outside line, which can also be referred to as trunk lines that connect to the PSTN, thereby allowing a user of the PBX to originate calls to users outside of the PBX and to receive calls from user outside of the PBX.
Telephone service providers that provide PBX service generally provide subscribing enterprises with additional services beyond those services available for PSTN subscribers. For example, a subscribing enterprise may have the option of receiving the services of forking and find-me.
Forking refers to a service that enables multiple phones, regardless of location, of a callee to receive the same call from a caller. For example, a callee can provide the telephone service provider with a list of phone numbers where the phone numbers correspond to, for example, the callee's office phone, home phone and cell phone. If the callee has the forking service, when a caller calls the callee, all of the phones referenced in the list receive the call and the callee can answer any of these phones to communicate with the caller.
A find-me service refers to a service that enables a callee to specify a list of phone numbers to the telephone service provider that can be called in sequence until the callee answers the call or the call times out. For example, the callee can specify that a call first be routed to the callee's office phone, then to the callee's cell phone and subsequently to the callee's home phone. In this case, when a caller calls the callee the call is routed to the callee's office phone. If the callee does not answer this phone within a certain amount of time, the call is rerouted to the callee's cell phone. If the callee does not answer the cell phone within a certain amount of time, the call is rerouted to the callee's home phone. In the case that the callee does not answer the home phone, the call may proceed to the callee's voice mail. If the callee answers the call with any of the phones, the call routing sequence is stopped.
In recent years, voice over Internet Protocol (VoIP) has provided an alternative to the conventional telephone exchanges. VoIP is a technology that allows a user to make telephone calls using an Internet connection instead of a conventional phone line and the conventional exchanges. VoIP uses the Internet as the transmission medium for telephone calls by sending voice data in packets using an Internet Protocol (IP) rather than by traditional circuit transmissions of the PSTN. A VoIP call may be carried by multiple routers over the Internet. VoIP is an attractive alternative to conventional telephony networks since a single network can be used to transmit both voice and data. Many organizations considering converging voice and data networks have found the costs of migrating to VoIP can outweigh the benefits. VoIP providers typically employ centralized PBX, provider-specific implementations that require expensive call servers and costly proprietary handsets.
Although VoIP providers typically provide services such as voice mail, caller ID, forking and call forwarding, the find-me service is unavailable. It is therefore desired that VoIP providers offer a find-me service to VoIP users. Further, it is desired that the find-me service provide greater flexibility than the find-me service offered to PBX users. Such flexibility can be the ability for a user to specify both parallel and sequential calling aspects.